Investigating the electrical behavior of nanoparticle infused holes on carbon fiber reinforced composites during fatigue loading

Abstract

One of the major problems and engineering issues in aircraft and automotive industries is galvanic corrosion on metal-metal and metal-composite interfaces. This occurs when two dissimilar metals or alloys are connected to each other at a common interface. Two metals, such as a carbon fiber-reinforced composite (CFRC) and a steel alloy, when joined together, experience galvanic corrosion at the joined interfaces because the difference in their electrical potentials and the presence of electrolytes or moisture causes the generation of galvanic cells. Carbon fiber being more noble than other metals and having excellent electric conductivity corrodes slowly. Therefore, the metals or alloys attached to a CFRC on an aircraft, automobile, or other structure corrode faster, and the resulting corrosion weakens the structural integrity of the composites. This thesis provides a detailed study of the mitigation of galvanic corrosion and improvement of corrosion resistance on a composite-metal joined structure. The experiments executed here were based on the application of 2, 4, and 8 weight percentages of nanoparticles (nanoclay and nanotalc) on a carbon fiber-reinforced composite hole having a baseline composition of epoxy resin (LOCTITE EA 9394). The composite specimens were treated with the nanoparticles and subjected to cyclic tensile loads on a MTS 810 test machine to investigate the variation of electrical resistance with respect to applied loads and time. The plots of resistance vs load and plots of resistance vs time mostly show an upward trend, indicating that with the application of nanoparticles as a sealant between two composite structures, the resistance to corrosion and deformation is increased, thereby decreasing the corrosive current throughout the composite surface. Nanoclay particles displayed a better performance, with the highest resistance measured at 43.9 ohms with the application of 8% wt% nanoclay particles.